In the oil and gas industry, hydrocarbons are accessed via a wellbore to provide a fluid flow path to a processing facility. Some of these hydrocarbon resources are located under bodies of water, such as lakes, seas, bays, rivers and/or oceans. To provide a fluid flow path from such locations, a pipeline may be installed with various segments of tubular members coupled together to provide a fluid flow path between the wellbore and the processing facility.
While the pipeline located on land may be easily inspected for leaks or other potential issues, leaks located within a body of water may be challenging to inspect. There are several methods proposed in the art to address the issues of leak detection for a pipeline located underwater (e.g., within or at least partially within the body of water). For example, Great Britain Patent No. 2382140 describes a method that involves the use of acoustic or other signal pulses to detect pipeline leakage. As another example, U.S. Pat. No. 7,728,291 describes a method that utilizes fluorescence polarization to detect viscous oil residues. Further, in Shari Dunn-Norman et al, “Reliability of Pressure Signals in Offshore Pipeline Leak Detection”, Final Report to Dept. of the Interior, MMS TA&R Program SOL 1435-01-00-RP-31077, pressure safety low alarms are described as being utilized to detect pipeline leakage. Also, other methods of different hydrocarbon detection technologies, may include the use of fluorometric sensors, acoustic sensor, methane sensor or a temperature sensor mounted on an remote operated vehicle (ROV) to detect pipeline leakage, as noted by Neptune Oceanographics Ltd (NOL), http://www.offshore-technology.com/contractors/pipeline_inspec/neptune/2011 (visited on Jul. 25, 2012).
While various different sensors may be utilized to detect the leaks, the movement of the sensors typically involves operators and other personnel to control and manage the operation via umbilical cables. For example, certain systems utilize a remote operated vehicle (ROV) for subsea leak detection. The ROV is equipped with a leak detection sensor to detect leaks. Unfortunately, as the ROV has to be manually controlled, the operation of the ROV involves a large amount of man hours to conduct such a survey for a pipeline. For example, U.S. Pat. No. 4,001,764 describes the use of a towing and recording boat to pull a SONAR sensor for pipeline leakage. This system requires operators to manage the towing boat and associated equipment.
Also, other technologies are provided that involve the use of vehicles to survey the seabed. For example, U.S. Patent Application No. 20110004367 describes a remote operated vehicle (ROV), which may be utilized for certain missions. Further, a GOSL publication describes the use of a Marport SQX-1 AUV capable of operating to 500 meters water depth, which may utilize sensors including SONAR. See Geodetic Offshore Service Limited (GOSL) (http://www.goslng.com/marport.asp) (visited on Jul. 25, 2012). However, this reference appears to rely only upon a methane sniffer for leakage detection, which can be result in reliability problems due to the lack of other sensor information.
As the detection of leaks is a time consuming operation, a need exists to enhance underwater leak detection methods and system and to enhance the operations to provide more confident results. In particular, a need exists to reduce operator and personnel associated with leak detection and provide an automated process that may be utilized to enhance operation and the processing of hydrocarbons. Further, a need exists for the AUV to avoid obstacles along the pipeline during the operations without user intervention.